The phenomena that occurs when an online chat morphs into two parallel conversations, usually as a result of one person continuing a conversation without realizing that the other person has changed the subject.

Person A: Yeah its funny how beer and weed can make you feel like you're peeing when combined.
Person A: Anyway, what's your favorite flavor of cotton candy?
Person B: Yeah this one time I smoked a spliff and downed a 40, and it felt like Niagara falls down there .
Person B: I'd have to say blue.
Person A: Hahaha! and agreed.
Person B: I like how you resolved our parallel chatting.